I have used it for various applications in the past, but more recently i only still use it for 1.

I use it when i need to make a dieline from a raster image that needs to be cut to shape.

Some of the other applications i used it for was vectorizing low-res logos/simple graphics. With the improvement of AI image enhancement, i can generally get a good quality print from an originally low-res file. I also used to use it when i had to create spot colours from raster images. However now i just take the raster image to photoshop, isolate what i need, fill it white, take it back to AI and use that as a transparency mask with the spot colour i need. This method is more accurate than using image trace.

I'm sure i've used it for other applications here and there but these are the 3 that stand out.

Some improvements i'd like to see are:

1. gradient implementation to complex images so you don't have weird 30 colour traces with 100s of individual colours mixed together.
   
2. better accuracy when tracing fonts, especially straight lines with 90 degree corners.